The subject matter described herein relates to refueling drogues. More particularly, the disclosure relates to refueling drogues which include power generation capabilities which may be used to power a control system for the drogue.
In order to extend the flight range of certain aircraft, some aircraft have been designed with in-flight refueling or air-to-air refueling capabilities. One type of refueling system is a hose and drogue system. The hose and drogue system includes a refueling hose having a drogue disposed at one end. A drogue is a funnel shaped device attached to the end of a refueling hose for connecting with the probe of another aircraft to be refueled in flight. The refueling hose connects to a Hose Drum Unit (HDU). When not in use, the refueling hose and drogue is reeled completely into the HDU. During operation, the refueling tanker flies straight and level and extends the refueling hose and drogue which trails behind and below the refueling tanker under normal aerodynamic forces. Tension on the refueling hose is aerodynamically balanced by a motor in the HDU so that as the receiver aircraft moves, the refueling hose retracts and extends in order to prevent bends in the refueling hose that may cause undue side loads on the refueling probe.
The second type of refueling system is a boom refueling system. The boom refueling system typically includes a rigid boom extending from the refueling tanker, with a probe and nozzle at its distal end. The boom also includes airfoils controlled by a boom operator stationed on the refueling aircraft. The airfoils allow the boom operator to actively maneuver the boom with respect to the receiver aircraft, which flies in a fixed refueling position below and aft of the tanker aircraft.
Although in-flight refueling is a relatively common operation, the aircraft to be refueled must be precisely positioned relative to the refueling tanker in order to provide safe engagement while the fuel is dispensed to the receiver aircraft. Different systems have been designed to automate the positioning process. For example, some boom refueling systems use cameras housed in the tanker aircraft to determine the distance between the receiver aircraft and the tip of a refueling boom carried by the tanker aircraft. The camera system can then be used to automatically control the position of the boom to mate with a corresponding refueling receptacle of the receiver aircraft.
In another system, a drogue can include movable, overlapping vanes and a canopy. The vanes may be moved to increase or decrease the size of the diameter of the drogue for high speed flight or for lower flight speeds. The drogue may include actuators to control the motion of the vanes and or the canopy. The motion of the actuators may be controlled by a guidance and control system. The guidance system can receive information corresponding to the current state of the drogue and a target state of the drogue. The guidance system can provide instructions to the control system that in turn directs the actuators to drive the configuration of the drogue from the current state to the target state.
The use of aerial refueling systems may be expanded if the refueling drogue had the ability to generate and store electrical power that could be used to run guidance and control systems of the refueling system. This would allow aerial refueling drogues to be retrofitable by bolting on to the end of the refueling hose of existing aerial refueling systems such as Wing Aerial Refueling Pods (WARPs) or Fuselage Hose Drum Units (HDUs). However, present refueling drogues do not have the ability to generate and store its own electrical power which to run the guidance and control systems.
Onboard wind mill generators located on the external surface of a drogue have been proposed to generate a small amount of power to help illuminate the drogue so the receiver aircraft pilot can see it during night refueling. However, wind mill generators are inefficient and may not be able to generate sufficient amounts of power to run guidance and control systems of the refueling system. These types of generators also take up valuable space under the drogue cowling, space that is needed for the guidance and control system.
Onboard battery packs have also been proposed to provide for a controllable drogue power system. However, battery packs only have a limited supply of power before needing to be recharged. In these systems, when the battery packs needed to be recharged, the drogue would have to be retracted back into the aerial refueling pods or HDU of the host aircraft. Once the batteries were recharged, the drogue could be re-extended to refuel again. This is a time consuming process. Furthermore, if the battery packs were to be depleted of power sometime during the refueling process, this could be problematic for the refueling tanker and the aircraft to be refueled.